Deuterium magnetic resonance (DMR) spectra of specifically deuterium labelled lipid molecules in aqueous suspension are being observed. The spectra show the characteristic Pake doublet of a partially disordered liquid crystal and allow determination of the deuterium order parameter which characterizes the motion of the carbon-deuterium bonds under the observation conditions. The deuterium labelled lipids have been reconstituted with bovine mitochondrial cytochrome c oxidase and the deuterium order parameters determined. This demonstrates that the lipid in the reconstituted lipid-protein particles is less ordered than the lipid alone under the same conditions. This result appears to disagree with those obtained by ESR techniques using spin labelled lipid in which protein is observed to further restrict the motion of the lipid. The explanation for these apparently opposite results is not yet clear, but it is likely that the critical issue is the time scale difference of the ESR order measurement and the NMR order measurements. Experiments are in progress to explore these questions.